1. Field of Invention
The present invention relates generally to impact printing devices for dot matrix printing in which a print wire is propelled against a printing medium by an associated plunger-type solenoid actuator and more particularly, the present invention relates to an improved matrix printer print wire solenoid constructed to provide quick assembly and disassembly of the component parts, thereby reducing the cost of its manufacture together with improving its reliability and performance.
2. Description of the Prior Art
Prior art print heads having plunger-type solenoids are generally constructed having a cap member mounted at one end of the solenoid which is crimped to hold the internal elements of the solenoid together. An example of this type of construction may be found in U.S. Pat. No. 4,272,748. Other plunger-type solenoids have utilized adjustable screw members for adjusting the load on the return spring member of the solenoid, after which the screw members are permanently secured to the solenoid. An example of this type of construction may be found in U.S. Pat. No. 3,994,382. Problems found with both types of construction include excessive cap member wear due to repeated impact of the returning plunger, uncontrolled variation in the length of movement of the plunger as a result of the crimping of the cap member, unreliable absorption of the impact of the rebounding plunger upon striking the cap member and an irrecoverable disassembly of the solenoid after crimping of the cap member has occurred.